1. Ultra Social Animal Main thesis: Humans are especially social. Social in the way that bees and ants are, yet bee and ant cooperativeness is based on kinship. Humans, by contrast, have a set of psychological mechanisms that compel ultra-sociality

2. Ultra Social Animal Two step processes to ultra-sociality: Obligate cooperative foraging. Created intrinsic motivation to cooperate Group competition: Created strong commitment to group and its cultural norms

3. Primate Cooperation Humans are primates and primates are social, but their sociality co-exists with strong intra- and inter- group competition. Among our closest relatives (chimpanzees and bonobos) foraging is largely solitary, in sharp contrast to humans where foraging is highly cooperative.

4. Primate Cooperation One important exception: chimps and bonobos occasionally hunt cooperatively. But on close examination this hunting is actually less cooperative than it looks. Why? Monkeys can’t be caught by a single hunter. A group must hunt if anyone is to get anything Follow the leader is pre- dominant strategy Getting kill or getting close to kill ensures largest proportion of spoils Individual interests realized in collective action

5. Primate Cooperativeness Chimpanzee cooperativeness limited by dominance: Researchers had children and chimps work together pulling on ropes to bring into reach a food reward. When reward was pre-divided into two equal piles chimps and children both cooperated effectively. When reward was in single pile chimp cooperation broke down. Why? Dominant chimp took all. Kids, by contrast, fairly easily divided reward equally.

6. Primate Cooperativeness Slight modification: if working independently and effort results in reward imbalance (pull on rope and get reward at the end), chimps never and children rarely shared (about 1/3 of the time). But if kids work collaboratively (both pull on single rope with two rewards at the end), and one gets more than the other, the lucky one shares, not so with chimps.

7. Effort-reward justice A concept that evolved over the course of human evolution. In another study where a second kid or chimp could help out or not in retrieving a reward, kids excluded a non-participant from getting part of the reward, whereas chimps did not. For chimps critical variable was simply proximity. Whether he/she had helped or not, if chimp close by, chimp got some of the reward.

8. Joint effort/mutual goal Communication on joint goal: present in children, not so in chimps; seems to cement commitment to shared goal. Forsaking one’s role in cooperative effort requires permission for kids, not for chimps. Understanding complementary roles in pursuing joint goal: kids seem to have “bird’s eye view” and can easily engage in role reversal, not so with chimps.

9. “I wanna help!” Children, but not chimps, seem intrinsically motivated to help each other. Tomasello argues this may be because our ancestors were inter- dependent on one another. “Help out today, because you may need a partner tomorrow” became an implicit part of our psychological make-up

10. Group competition Selected for organization and cooperativeness at the group level. So how does a group member show others that he/she is a good, trustworthy, cooperative partner? Ans: displays of commitment to group norms.

11. Groupishness: Chimps vs. children Both chimps and children show evidence of being influenced by majority decision. Both will make a selection based on the number of others who have made the same selection. But only kids will make that selection contradicting their own earlier experience, having made an earlier, different decision that led to a reward.

12. Groupishness: Chimps vs. children Children, but not chimps, also seem motivated to enforce group norms on others, but only conventional norms on other group members. Group norm: moral rule “no bad words” Conventional norm: keep to the right in the hallway